This invention relates to dose dispensing apparatus, particularly though not exclusively for dispensing doses of drugs and other like medicaments. It can, however, be used in analogous areas where controlled dispensing of material is desired. It is of particular value for dispensing measured doses of fluent medication from a storage container containing a reservoir of such medication, although it can also be used to dispense unit dosages of solids each as, for example, tablets.
Pharmaceutical packaging is normally designed to make access by the patient easy and unrestricted. There are, however, situations where considerations of safety and security make it necessary to control and record the usage of medicines by patients. Additionally, supervision of dosage by medical, nursing and care staff is time-consuming and costly, particularly if the patient is not in hospital or other care facility. This is especially the case if the patient needs to take a combination of medicines with a strict regime of medication. Also, while in the case of many medicaments and pharmaceuticals the dosage regime may be subject to wide variation without potential danger to the patient on the one hand or loss of effectiveness of the medication on the other, it is well understood that medication is desirably effected using a regular dosage regime. It is found that this is not always easiest achieved simply by relying on a patient to follow written instructions. Attempts have accordingly been made to develop devices which are themselves essentially “programmed” to dispense medicament at the correct intervals, but such systems have tended to be of narrow applicability and complex and, indeed, to be easily defeated. Thus, suggestions have been made in the case of multiple pill-based medication regimes, to provide automated dispensing devices. U.S. Pat. No. 5,752,621 and U.S. Pat. No. 5,472,113 both disclose apparatus which can be used to dispense, at appropriate times, various pills in appropriate combinations. Further prior art dispensing apparatus is referred to in each of these specifications.
Devices for dispensing fluent materials such as drugs and medicaments are known in a wide variety of forms. Generally they consist of a container which is sealed and from which a suitable dose of material may be ejected. One particular widespread presentation for drugs, particularly the treatment of asthma, is that of a small pressurised canister having a valve at one end and a dispensing tube fitted with a nozzle. So-called inhalers are well-known and widely used by asthmatics. In principle, however, such a presentation is not in any sense restricted to drugs for use in treating asthma, but can be used for a wide variety of medicaments and pharmaceuticals. The mode of administration additionally does not always have to be by way of an aerosol spray. For example, it is entirely conceivable to dispense pasty or creamy formulations from a canister with some form of pump valve on it. Even discrete dosage forms such as pills may be presented in containers from which pills may be released one at a time. This is a particularly preferred dosage approach presentation for homeopathic remedies where it is believed highly desirable that the pill may be taken without being handled by the person taking it more than strictly necessary. Alternatively, pills may be incorporated into a strip or ribbon which may be fed out from a cassette or the like one by one, and released from the strip for administration.
A separate consideration in connection with the administration of medicaments arises in the case of controlled clinical trials, or even, though to a lesser extent, patient monitoring. It is particularly important in a controlled clinical trial to ensure not only that the dosage regime is followed, but that a positive record is secured which enables that to be verified. Any such system should, of course, not be capable of being falsified by the patient.
A further separate consideration which applies in some cases is the strong desirability of avoiding overdosing. This can be of particular importance in the case of medicaments used in diabetes treatment where they can have extremely adverse effects if not used in the right quantity at the right time.
Yet a further problem which arises in connection with the controlled administration of medicaments in unsupervised conditions is to ensure that the right medicament is being administered, and in the case of controlled or prescription medicines, that no diversion occurs.